A combined cytological and biochemical study of DNA amplification in oocytes is proposed. In order to determine whether gene amplification is a general phenomenon associated with oogenesis RNA-DNA hybridization analysis will be carried out on oocytes containing large masses of extrachromosomal nucleolus-associated DNA, and on oocytes in which such DNA cannot be detected; on oocytes which develop multiple nucleoli, and on oocytes in which the nucleolus remains singular throughout oogenesis; on oocytes the nuclei of which show little or no RNA synthetic activity, this function being carried out by polyploid nurse cells which provide most of the RNA accumulated by the oocyte, and on the nurse cells themselves. Cytological studies will be carried out on the same oocytes in order to localize the amplified genes and to show their relationship to other structures within the nucleus. The objective of the proposed research is to determine whether amplification represents a generalized phenomenon associated with oogenesis; to determine the extent of diversity which exists in regard to the degree of amplification and the nature of the amplified DNA; and to correlate this diversity with differences in the organization of amplified DNA.